Carbohydrates and Lipids Flashcards
describe the chemical formula for carbohydrates
(CH2O)n n=3
what is the most abundant class of biological molecules
carbohydrates
what are carbohydrates primarily formed by
photosynthesis
what are the basic units of carbohdryates known as
monosaccharide
what are 2 types of functional groups of carbohydrates
aldehyde or ketones
what are monosaccharides
simple sugars = monomer
what are disaccharides
2 simple sugars linked by covalent bond
what are oligosaccharides
2 simple to 10 sugars linked by covalent bond
what are polysaccharides
hundreds/ thousands of monosaccharides linked by covalent bond- starch, glycogen, cellulose
name the monosaccharides that contain 3,4,5,6,7,9 carbons
3- triode
4- tetrose
5- pentose
6- hexose
7- heptose
9- nonose
what are the most commonly occurring monosaccharides
fructose
glucose
galactose
what is fructose found in
fruits, vegetables and honey
derived from digestion of sucrose
what is glucose found in
some fruits, vegetables and honey
manufactured foods
digestion and conversion of other carbohydrates
what is galactose found in
digestion of lactose
it is similar to glucose but differs by 1 OH group
what are disaccharides and what is the resulting molecules
covalent bonds between the numeric hydroxyl of a cyclic sugar and the hydroxyl of a second sugar are termed glycosidic bonds
- result molecules are glycosides
what are nutritionally important disachhrairdes
sucrose, lactose and maltose
describe where lactose if found and the bonds found within it
- in milk of mammals
- consists of galactose and glucose in a B-(1-4) glycosidic bond
describe where sucrose is found and what bonds it contains
- table sugar, and sucrose in manufactured foods- derived from sugar cane and sugar beets
- sweet root vegetables such as beetroot and carrot
consists of glucose and fructose in an a-(1,2) glycosidic bond
describe where maltose is found and what bonds it consists of?
- intermediated in the intestinal digestion of glycogen and starch
- malted wheat and. barely- fermented into beer
consists of glucose and glucose in an a(1-4) glycosidic bond
what are oligosaccharides
chains of 3 or more monosaccharides linked together by glysocsidic bonds
what are polysaccharides
high molecular weight polymers
- comprised of multiple monosaccharides joined by glycosidic linkages
- the monomeric building blocks used to generate polysaccharides can be varied
what is the predominant monosaccharide found in polysaccharide
D glucose
( starch,glycogen, and cellulose, are composed of D glucose)
what bond does starch and glycogen
alpha 1,6 glycosidic bond
what is the major form of stored carbohydrate in plant cells
starch
what is unbranched and branched starch
amylose - unbranched starch
amylopectin - branched starch
what bonds does amylopectin have
alpha 1-6 glycosidic and alpha 1-4 glycosidic bond
what is the major form of stored carbohydrate in animals
glycogen
what bonds does glycogen have
homopolymers of glucose in a-(1,4) linkage; it is also highly branched with a(1,6) branch linkages occurring every 8-10 res
describe the structure of glycogen
very compact structure that results form coiling of the polymer chains
the compactness allows large amounts of carbon energy to be stored in a small volume, with little effect on cellular osmolarity
how are carbohydrates synthesised
formed in the plants by photosynthesis from carbon dioxide and water in the presence of sunlight.
what does light dependant energy involve?
light energy converted to chemical energy by taking photons and water and producing oxygen as well as high energy molecules including ATP, ADP and NADPH
what is the light independent reaction
Calvin cycle - involves input of carbon dioxide as well as ATP and NADPH to produce carbohydrates such as glucose
where is carbohydrates found?
wide array of foods: bread, beans, milk, popcorn, potatoes , spaghetti, soft drinks, corn, etc
sugars, fibres and starch most abundant form
give examples of polysaccharides that break down to disaccharides and monosaccharides
- digestion of carbohydrate is performed by several enzyme
starch and glucagon are broken down into glucose by amylase and maltase. Sucrose and lactose are broken down by sucrase and lactase respectively
describe carbohydrate synthesis
-Blood sugar levels can become low if the food isn’t broken down
Glucose blood levels must be maintained as it is used by cells and ATP
-Gluconeogenesis - can synthesis glucose
-Involves precursors such as glycerol which is produced by breaking down triglycerides.
-Anaerobic metabolisms can produce lactate which is taken to the liver where it is converted into pyruvate
-Another precursor are AA derived from breaking down of proteins
-These AA are converted into pyruvate or intermediates of citric acid cycle
-So pyruvate and oxaloacetate can then be used to generate glucose
-Once glucose is produced through gluconeogenesis in the liver, it is then released into the bloodstream where it can travel to sense other parts of body for energy
What the 5 primary functions of carbohydrates
- energy production
- energy storage
- building macromolecules
- sparing protein
- assisting in lipid metabolism
what does th breakdown of glucose produce
Adenosine triphosphate (ATP)
where does the enrgy from glucose come from
chemical bonds between the carbon atoms (cells in our bodies break these bonds and capture the energy to perform cellular respiration)
how does glucose provide energy with adequate and inadequate oxygen
1st step of breaking down glucose- glycolysis - glucose converted to pyruvate where ATP is produced
There could be adequate oxygen or not
In the case of adequate oxygen
The glucose goes through metabolism pathways of aerobic respiration
In this process, pyruvate is converted to acetyl CoA which goes through krebs cycle
Which moves through electron transport chain where kass of ATP is produced where most of energy comes from
Inadequate oxygen
- pyruvate converts to lactic acid where it is transported to liver where it is converted to glucose which is used in blood to maintain constant glucose concentration and constant supply of ATP in tissues
if the body has enough energy what is excess glucose stored as and where is it stored
glycogen
stored in muscle and liver
what can glucose be converted to?
- converted to ribose and deoxyribose
- essential building blocks of important macromolecules such as RNA, DNA and ATP
- Glucose is additionally utilised to make molecules NADPH
what does NADPH stand for and what is its importance
- nicotinamide adenine dinucelotide phosphate
- an important for protection against oxidative stress and is used in many other chemical reactions in the body
what is lipid metabolism associated with
carbohydrate metabolisms as products of glucose ( acetyl CoA) can be converted into lipids
how is the BMI caculated and what is classed as underweight, ideal, overweight and obese?
BMI - weight in KG divided by height in m2
bM1- 18.5 - underweight
BMI between 18.5 and 24.9 - ideal
BM1 - 25 -29.9 - overweight
BMI - over 30- obesity
how much carbohydrate intake contributes to daily energy requirement
of this how much free sugars and natural sugars contribute to daily energy requirement
total carbs contribute 50% towards daily energy requirement
free sugars - 5% of daily energy requirement
natural sugars 45% of daily energy requirement
what is the dietary fibre intake?
30 g/day
children 2-5 = 15g/day
chidlren 5-11= 20g/day
children 11-16 = 25g/day
adolescents 16-18 = 30g/day
what is the definition of a lipid
- biological molecules that are insoluble in aq solutions and soluble in organic solvents are classified as lipids
what examples are lipids
include fats, oils, certain vitamins ( such as A, D,E and K), hormones and most of cell membrane that is not made up of protein
how are lipids classified
- fatty acids and its derivatives
- cholesterol and its derivatives
- lipoproteins
what are saturated fatty acids
- fatty acids that contain no carbon- carbon double bonds
what are unsaturated fatty acids
contain double bonds
what are fatty acids
long chain hydrocarbon molecules containing carboxylic acid moiety at one end
describe some properties of saturated fatty acids
- very stable - not prone to rancidity
- straight chains stack tightly
- solid at room temperature
- found in butter, animal fats, eggs,coconut oil, palm oil and in your body
what is monosaturated, polyunsaturated fatty acids
monounsaturated - molecules with one double bond
polyunsaturated - molecule with 2 or more double bonds
what are 2 possible configurations for fatty acids
cis configuration- adjacent carbons lie on same side of double bonded carbons, one occurring in all biological unsaturated fatty acids
Trans configuration - adjacent carbons lie on opposite sides of double bonded carbons
describe properties of unsaturated fatty acids
- double bond prone to rancidity
- bent chains do not stack as tightly
- liquid at room temperature
- found in plant oils
which fatty acids can animals not synthesis
essential fatty acids such as linoliec acid
need to be obtained by diet
name 2 complex lipid molecules
triglycerides - ester derived form glycerol combined with 3 fatty acid molecules
phospholipid- group go polar lips that consist of 2 fatty acids, a glycerol unit and a phosphate group which is esterfied to an organic molecules such as choline ehtanolamine, inositol
how efficient are trigylercide in means of storing fatty acids
- very effiencet = long term energy storage
- large moelcuels = high potential energy
- gram for gram more than twice the energy of carbohydrates
where is accumulation of triacylglyercols
cytoplasm of adipocytes
name properties of triglycerides
- store fatty acids
- fat deposits under skin and throughout body cut heat loss by 2/3
- protects and cushions organs
what roles do phospholipids play in cells
- in forming the permeability barrier of the cell membrane and intracellular organelle
- in prodding the supporting matrix and surface for many catalytic processes
- in actively participating in signal transduction in response to both external and internal stimuli
- in providing precursors for signalling processes and macro molecular synthesis
what are steroids
lipids characterised by a carbon skeleton consisting of four fused rings
- vary from one anohjter; in the nature of attached groups and the position of the groups
what is cholesterol
- special type of lipid
- maintain membrane fluidity
- involved in production of hormones and vitamin D
- produced by our liver (75%) and obtained through our diet (25%)
- transported in blood by a lipoprotein
where is cholesterol mostly made by the body and what is it carried in blood as
made by body in th liver
- LDL (low-density lipoprotein)
-HDL (high density lipoprotein)
what is LDL and what can raise LDL
LDL- stores cholesterol in the blood stream
too much saturated fats can raise it - increasing the risk of heart disease and stroke
HDL- regulated LDL storage and promotes secretion
positive effect by taking cholesterol from parts of the body where there’s too much of ti to the liver, where its disposed of
how much saturated fat should we eat
men should not have more than 30g a day
women should not have more than 20g of fat a day
children should have less
